Extreme low-carb diets 'not recommended,' study says

An extremely low carbohydrate diet is not recommended because there are insufficient scientific grounds to ensure safety from nutritional problems such as loss of muscle mass, the organization said in a document released Monday. It said research now needs to be carried out to find appropriate carbohydrate intake levels.

The document was compiled by the organization's committee on dietary treatments, chaired by Kazunori Utsunomiya, after studying published findings in and outside Japan.

Focusing on the conventional emphasis on restricting total energy intake, the document says scientific evidence on proper intake levels for Japanese is inconclusive because studies in Europe and the United States have surveyed patients with a body mass index (BMI) of 30 to 35, much higher than those of most Japanese patients.

The committee said the ideal nutritional proportions are 50 to 60 percent carbohydrates, 20 percent proteins, and the rest fat. But it acknowledges the possibility of reducing carbohydrates, saying, "It is possible to recommend lowering the carbohydrate intake percentage from 50, depending on the preferences and clinical conditions of the patient."

Utsunomiya, a professor at Jikei University, said: "While the extreme restriction of carbohydrates may cause nutritional problems, it is possible to lower the carbohydrate intake percentage by balancing it with other nutrients. We will keep studying to set the proper criteria" for Japanese.